<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>js数字</title>
</head>

<body>
    <script>
        var x1 = 34.00;
        var x2 = 34;
        var y = 123e5;
        var z = 123e-5;
        document.write(x1 + "<br>");
        document.write(x2 + "<br>");
        document.write(y + "<br>");
        document.write(z + "<br>");
    </script>
</body>

</html>